For conventional digital cameras, there have been devised and manufactured systems for recording image data of a taken image or voice data on an internal recording device or a removable recording medium, and connecting to an information processor such as a personal computer (hereinafter simply referred to as “PC”) with a cable or the like to transfer the information such as the image data recorded on the recording device or the like. Furthermore, recently, systems for performing printing, not via a PC, but by directly connecting a digital camera and a printer with a cable, have been manufactured.
In such systems, a digital camera and a PC are usually connected via a wired interface such as a USB (universal serial bus), and data exchange is performed between the equipment in accordance with a determined protocol. For example, as protocols for data exchange between a PC and a digital camera, a PTP (Picture Transfer Protocol) specified in a Still Imaging Device Class of USB devices, and a protocol defined in a Mass Storage Device Class, are used.
There is also proposed a standard called PictBridge as a mechanism for directly connecting a digital camera and a printer. According to Version 1.0 of this standard, there is provided a configuration in which a user can utilize operation members, such as switches and operation buttons, and a display device, such as an LCD, on the digital camera side, to select an image to be printed or issue a print instruction when mutual connection is completed. This applicant also proposes the content described above in Japanese Patent Application No. 2004-030838 and the like.
Meanwhile, when a digital camera and a PC are connected with each other, it is common to perform operations on the PC side, and it is not common to cause operations to be performed on the digital camera side.
However, as digital cameras are increasingly spreading, the rate of users unfamiliar with operating a PC is increasing. Accordingly, there is demand for handling images and the like taken by a camera without operating a PC as far as possible.
Accordingly, this applicant has also already proposed a technique in which operations on the camera side are enabled when a PC is connected, under the control of the PC, so that images and the like are displayed on a display device implemented on the camera, and the images and the like are transferred to the PC by operations on the camera side.
As described above, though, conventionally, it is a main purpose to simply transfer image data in a camera to a PC, which is an external device, to store and review it, applications in which a PC and a camera operate in conjunction with each other are increasing recently.
Meanwhile, it has been proposed to adapt digital equipment (devices) to be appropriate for a network, and a mechanism has been sought for enabling devices to communicate with one another by applying the so-called Internet technology. There are also devised network devices, such as a network printer and a network camera, each of which has an IP address and is appropriate for operation control utilizing the TCP/IP protocol, and a part of the network devices are put into practical use.
Furthermore, recently, wireless network technology has been advanced, and it is being promoted to incorporate a wireless communication function in conformity with standards, such as Bluetooth and IEEE 802.11x, into a device.
There is an example in which, in such a case, a procedure is performed for using a discovery method specified in UPnP (Universal Plug&Play) to search for each device, and retrieving and connecting a necessary service and device is performed. It is also proposed to automate parameter setting for wireless connection (Japanese Patent Laid-Open No. 2002-359623).
In this method, the side which searches for a device or service (hereinafter referred to as “a control point”) and the side which provides a service are separated, and search information is delivered over a limited network by utilizing the mechanism of UDP multicast. Then, a device having a service capable of responding to it returns a response so that mutual recognition can be performed.
In the case where multiple control points exist, each control point performs UDP multicast to perform a search. A device capable of providing a service returns a response to each control point in response to the search. According to this discovery method, it is possible to perform mutual recognition between each control point and a service or device.
However, in the present situation, it is mainly products such as a network router and a wireless access point that utilize the above-described discovery method to perform mutual recognition and exchange data on a network. As for these products, a logical connection state between a control point and a service-provision device is completed for each operation in many cases.
For example, in the case of an HTTP or FTP server, the number of clients which can be connected at the same time is often determined by the server side in consideration of the capacity of the server side. When the connection state is kept with multiple clients at the same time, the capacity on the server side must be considered so that equal services can be provided to a predetermined maximum number of communication counterparts.
If a client appears after the maximum number of connections has been established with the server, and this client attempts to connect to the server, any one of the connections must be released to keep the number within the maximum number, or the new connection request by the client must be rejected.
When a case is considered where an image input device such as a digital camera connects to such a network, it is conceivable that counterparts to which the image input device can provide services are extremely limited because its resources as a device are extremely poor in comparison with a conventional server. As an extreme example, it is assumed that a device can connect to only one client at the same time, and, as described above, there are multiple control points, which recognize this device at the same time. In this case, if any one control point makes a logical connection to utilize a service of the device, the other control point cannot utilize a service of the device.
In a conventional idea, since it is common that a device such as a digital camera is accessed by operation on the side of a control point such as a PC, it is not necessary to especially consider such a problem. However, it is also conceivable that, for example, a user desires to operate a digital camera, which is on a service-provision side, to connect to a particular PC and push data into the PC from the camera side. In such a case, if a client which is an undesired communication counterpart connects to the camera earlier, the camera cannot connect to a desired client to provide a service.
Thus, when a device with relatively poor resources connects to a network, it is required to consider different use cases such as:                a case in which a service-provision device is selected by operation by a user from a client, and a client which connects earliest can connect to the device; and        a case in which connection with a particular counterpart is assumed, and connection with the counterpart is made by operating the device.        